Modifying the mirrors on each of my 4 previous was my first order of business!
same here, have yet to ride a bike with stock mirrors that see past my shoulders
I like to have mirrors that merge with my peripheral vision. I find bar end mirrors work well, I have a set of Doubletake mirrors on my K-Pipe, they use a RAM mount system
I adjust my mirrors so that only eye movement is required, I dunno, how often do I check, depends if some Ahole is tailgating me